Deliverability & sending infrastructure
Everything that gets a cold email into the inbox instead of spam: domain setup, authentication, warmup, volume pacing, and reputation monitoring.
Since the Google and Yahoo bulk-sender rules of February 2024, deliverability is a hard technical gate, not a soft best practice. Cross the thresholds and your mail gets throttled or blocked.
The hard numbers
Spam complaint rate must stay below 0.30% (target under 0.10%). Bounce rate under 2%. These are the two most defensible numbers in outbound; everything else is a range.
Domain and mailbox architecture
Send from secondary domains, not your primary. Two to three mailboxes per domain, never five or more. Ten to twenty cold emails per mailbox per day is the safe range in 2026, never near 100.
Authentication and warmup
SPF, DKIM, DMARC alignment, and one-click unsubscribe (RFC 8058). Warm every new mailbox for two to four weeks before real sending, then keep ongoing warmup traffic.
Monitoring
Watch Google Postmaster Tools and your spam rate continuously. Reputation is slow to build and fast to lose; treat “guaranteed inbox” vendor claims skeptically.
Keep reading
All guides →Enrichment waterfalls
Chain data providers in sequence so a miss from one becomes a hit from the next, maximizing coverage while paying mostly on verified data.
BuildSignal-based outbound
Trigger outreach off buying signals that mark an account entering a buying window, instead of blasting a static ICP list.
BuildAI & agentic workflows
Use LLMs as per-row functions and research agents inside GTM workflows: classification, extraction, qualification, and first-draft personalization at list scale.